Blood Lead Levels in U.S. Children Ages 1-11 years over the 40-year period from 1976 to 2016

BACKGROUND AND AIM: Blood lead levels (BLLs) have generally declined over the past 40 years in the United States (U.S.).We describe the distribution of BLLs in U.S. children age 1-11 years from 1976-2016 and associations with demographic, housing and regional characteristics. METHODS: Data from the National Health and Nutrition Examination Survey (NHANES) II, NHANES III 1988-1991 and 1991-1994, and 1999-2016 NHANES cycles were used to describe the distribution of BLLs in U.S. children age 1-5 years and 6-11 years from 1976-2016. For all children with valid BLLs (n=27,122), geometric mean (GM) BLLs (95% confidence intervals [CI]) and estimated prevalence were calculated overall, stratified by age group (1-5 years; 6-11 years) and selected characteristics. RESULTS:The GM BLL in U.S. children age 1-5 years has declined from 15.2 µg/dL (CI 14.3,16.1) in 1976-1980 to 0.83 µg/dL (CI 0.78,0.88) in 2011-2016, representing a 94.5% decrease over time. A large portion of this decline occurred before 1992 as GM BLLs for 1-5 year olds had decreased to 3.6 µg/dL (CI 3.2,4.0) by 1988-1991. For children age 6-11 years old, GM BLL have declined from 12.7 µg/dL (CI 11.9,13.4) in 1976-1980 to 0.60 µg/dL (CI 0.58,0.63) in 2011-2016, representing a 95.3% decrease. As with the younger age group, much of this decrease occurred before 1992. Despite this substantial decline, disparities exist by income, race/ethnicity, and housing age. CONCLUSIONS:Lead exposure in U.S. children age 1-5 years and 6-11 years has substantially decreased over this forty-year period. Despite this significant achievement, children, particularly those of minority and low-income backgrounds, are still at risk of lead exposure. Risk factors, such as income and housing age, persist throughout regardless of child’s age. NHANES estimates of BLLs have played a key role in monitoring the decline in BLLs in U.S. children and have influenced public health action and national policy around childhood lead exposure. KEYWORDS: Epidemiology, children's environmental health, heavy metals